1. Field of the Invention
The present invention relates to a suspension type hoisting apparatus which has an elevating portion elevatably suspended from a base (for example, a carriage) via a suspension member and is able to suppress sway of the elevating portion in a short time.
2. Description of the Prior Art
There are many cases where a transfer apparatus, in which a suspension type hoisting apparatus (so-called crane) is incorporated, is frequently used as transfer equipment of loads in, for example, a factory. One example of such a transfer apparatus is illustrated in FIGS. 21(a) and 21(b).
The transfer apparatus AO, shown in FIGS. 21(a) and 21(b), is constructed and provided with a carriage 103 moving along a rail 102 disposed at the ceiling 101, a suspension member 104 suspended from the carriage 103, and an elevating portion 105 attached to the lower end portion of the suspension member 104. A hand 105a which is able to hold an appointed load 106 is integrally attached to the elevating portion 105. The suspension member 104 is wound and unwound by a winding device (not illustrated) which is attached to, for example, the carriage 103 side, whereby the elevating portion 105 is elevated and lowered.
When the load 106 is transferred by the transfer apparatus AO, first, as shown in FIG. 21(a), the carriage 103 is stopped right above the load 106, and the elevating portion 105 is lowered to cause the hand 105a to hold the load 106. And, the elevating portion 105 is elevated to an appointed position with the load 106 held, and the elevating portion 105 is fixed at the carriage 103, wherein the load 106 is transferred by the carriage 103 to a reference position along the rail 102 in a state shown in FIG. 21(b). When the load 106 arrives at the reference position, the carriage 103 is positioned right above a placing position of the load 106, and the load 106 is placed thereon by lowering the elevating portion 105 again.
By repeating the operations, loads can be efficiently carried or transferred, utilizing space in the vicinity of the ceiling, wherein there are comparatively few obstacles.
However, since the conventional transfer apparatus AO is constructed so that the elevating portion 105 is suspended by the suspension member 104, the elevating portion 105 constitutes a pendulum, using the carriage 103 as a fulcrum. Therefore, for example, when the elevating portion 105 is elevated or lowered, sway occurs at the elevating portion 105, which is responsive to inherent frequency determined by the length of the suspension member 104. Therefore, in the conventional transfer apparatus AO, even though the carriage 103 reaches the reference position and causes the elevating portion 105 to be lowered, a load 106 can not be held by the hand 105a or a held load can not be placed by the hand 105a until the sway of the elevating portion 105 stops, wherein transfer efficiency is adversely influenced.
Furthermore, although a passive sway controlling device (for example, movement absorbing device, damper, etc.,) has been attached as a countermeasure, it is very cumbersome to adjust the sway controlling device, for example, in a case where the stop height of the elevating portion 105 differs.
The present invention was developed in view of the above-described drawbacks, and it is an object of present invention to provide a suspension type hoisting apparatus which is able to remarkably improve working efficiency by effectively stopping sway of the elevating portion.
In order to achieve the above-stated object, the present invention provides: a suspension type hoisting apparatus, which is able to adjust the position of an elevating portion elevatably suspended from the base via the suspension member by an elevating portion position controlling device, which is constructed and provided with a means for positioning a suspension member suspended from the base in the horizontal plane; a position controller for outputting a velocity reference signal on the basis of a deviation between a position reference signal and actual position with respect to the positioning means; and a velocity controller for outputting a force reference signal being a manipulated variable of the positioning means, on the basis of a deviation between the velocity reference signal outputted from the position controller for the positioning means and actual velocity, wherein, the elevating portion position controlling device includes a sway velocity detecting means for detecting a sway velocity of the elevating portion; a sway stop compensation portion for outputting a sway controlling signal for the positioning means on the basis of output from the sway velocity detecting means; and an adder portion for adding the sway controlling signal outputted from the sway stop compensation portion to an appointed signal on the control loop of the elevating portion position controlling device. Thereby, since it is possible to effectively stop sway of the elevating portion and to carry out positioning thereof by a simple control system, remarkable improvements in working efficiency can be secured.
Herein, the force reference signal outputted from the velocity controller, the velocity reference signal inputted into the velocity controller, or a position reference signal inputted into the position controller is considered as the appointed signal on the control loop of the elevating portion position controlling device, to which the sway controlling signal is added.
Furthermore, in a case where the base is constructed of a carriage, a moving means of the carriage may be used as the positioning means. However, in this case, the positioning direction is limited to the moving direction (for example, direction of a rail) of the carriage.
Furthermore, the sway stop compensation portion may be composed of a proportional element, for example, the value of which is established in compliance with a stop height of the elevating portion.
Still furthermore, in order to prevent a servo system from oscillating due to observation noise, it is preferable that a filter for eliminating such observation noise is attached to the sway stop compensating portion.
In a case where the sway velocity detecting means is composed so as to detect the relative sway velocity of the elevating portion with respect to the base, it is preferable that the sway velocity detecting means is further provided with a elastic vibration component detecting means for detecting elastic vibration components produced at the base, and an excluding means for influences due to the elastic vibration components from sway control made by the sway stop compensation portion on the basis of the elastic vibration components detected by the elastic vibration component detecting means.
Herein, the excluding means, for example, may be constructed so that it excludes influences, resulting from the elastic vibration components, from the sway control by adding elastic vibration compensating signals generated on the basis of the elastic vibration components detected by the elastic vibration component detecting means to the sway controlling signals outputted from the sway stop compensation portion. At this time, the elastic vibration compensating signal may be generated by a elastic vibration component compensation portion including a band pass filter to exclude noise components contained in the elastic vibration components detected by the elastic vibration component detecting means and a phase compensation portion for compensating a phase between the relative sway velocity of the elevating portion and the elastic vibration components.
Furthermore, the excluding means may be composed of a notch filter for suppressing the elastic vibration components from signals corresponding to the sway velocity of the elevating portion. In this case, a frequency band suppressed by the notch filter is adjusted on the basis of the elastic vibration components detected by the elastic vibration component detecting means.
Here, the elastic vibration component detecting means may be composed so that, for example, signals corresponding to acceleration signals of the elastic vibration components can be detected.
Furthermore, the sway velocity detecting means for detecting the relative sway velocity for the base of the elevating portion is provided with, for example, a light emitting means installed on the base or the elevating portion, a lens installed on the elevating portion or the base opposite to the light emitting means, which focuses light coming from the light emitting means, a light receiving position detecting element installed on the elevating portion or the base and used to detect the light receiving position by receiving light focused by the lens, wherein the sway velocity detecting means detects relative positions of the elevating portion with respect to the base one after another on the basis of the light receiving position detected by the light receiving position detecting element, and at the same time detects relative velocitys of the elevating portion on the basis of the detected relative position of the elevating portion.
Furthermore, if the sway velocity detecting means is further provided with at least two light emitting means and a calculating means is provided, which calculates a position of the elevating portion in the horizontal direction, a position of the elevating portion in the perpendicular direction and a rotating angle around the perpendicular axis with respect to the base on the basis of the detection results of the light receiving position detecting element with respect to the respective light by alternate blinking of the respective light emitting means, accurate and high velocity position detection is enabled by a simple construction without any image processing, etc.
Furthermore, if the plurality of light emitting means are provided in a plurality of sets with the installation interval of these light emitting means changed, and one set of the plurality of sets of light emitting means is selectively used in compliance with an elevation length of the elevating portion, the range of detection can be prevented from being decreased as much as possible if the distance between the base and the elevation port is close to each other, and detection accuracy can be prevented from being lowered in a case where the distance between the base and the elevating portion is far.
Furthermore, if a lighting state detecting means is provided, which detects the lighting state of the light emitting means on the basis of a quantity of light received by the light receiving position detecting element, and the detection results of the light receiving position detecting element are acquired by, the calculating means on the basis of the lighting state of the light emitting means, which is detected by the lighting state detecting means, it is not necessary to provide any electric wiring between the base and the elevating portion, and even though the light emission timing of the light emitting means is changed, it is not necessary that the acquisition timing of the light receiving position is changed in line therewith.
Furthermore, it is assumed that the sway velocity detecting means is further provided with a memory element for temporarily holding the light receiving position detected by the light receiving position detecting element, the memory element is renewed on the basis of the lighting state of the light emitting means, which is detected by the lighting state detecting means, and the calculating means carries out the calculation at every appointed interval of time on the basis of the light receiving position temporarily held in the memory element, wherein, the calculating means is able to acquire the light receiving position from the memory element at an interval matched up to a light emitting timing of the light emitting means without providing connection wiring between the base and the elevating portion.
Furthermore, a variable stop means for varying the quantity of light incident into the light receiving position detecting element and a stop controlling portion for controlling the variable stop means in compliance with an elevation length of the elevating portion are provided, wherein, for example, by controlling the opening diameter of the variable stop means so as to decrease in line with an increase in height of the position of the elevating portion, it is possible to prevent a light spot from broadening on the light receiving position detecting element even though the distance between the elevating portion and the base is decreased, and it is possible to prevent the range of detection from being decreased. Still furthermore, in addition thereto, fluctuation, in a short or long distance, of the light receiving quantity of the light receiving position detecting element can be decreased, wherein the position detecting accuracy thereof can be improved.